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(No Mode-1.) L 2 Sheets-Sheet 1.

l C. E. DAVIS.

' ELECTRIC DRILL. No. 583,407. Patented May'25,1897.

(No Model.)

Q E DAVISl l l Z'Sheets-Sheet 2l ELECTRIC DRILL.

if? [L Patented May 25,1897.

nnnnnn n MT M L UNITED STATES PATENT OFFICE.

CHARLES E. DAVIS, OF CHICAGO, ILLINOIS, ASSIGNOR TO ARTHUR D. DANA,TRUSTEE, OF SAME PLACE.

ELECTRIC DRILL.'

SPECIFICATION forming part of Letters Patent No. 583,407, dated May 25,1897.

Application filed April 27, 1896. Serial No. 589,247. (No model.)

To all whom t may concern:

Be it known that I, CHARLES E. DAvIs, a citizen of the United States,residing at Chicago, in the county of Cook and State of Illinois, haveinvented certain new and useful Improvements in Electric Drills, ofwhich the following is a specification.

My invention relates to drills to be used in drilling holes in coal orother material, and has for its object to provide a newr and improveddrill, of which the following is a description.

My device is illustrated in the accompanying drawings, wherein- Figure lis a perspective view of a drill operated by an electric motor, themotor being in place upon its supporting-frame. Fig. 2 is a sectionthrough the armature-shafE-into which the drill is received. Fig. 3 is afront end view of the drill and associated mechanism with parts brokenaway. Fig. 4 is a plan view of the feed-nut. Fig. 5 is a view of aportion of the drill-shaft, showing the keyway cut therein.

Like letters refer to like parts throughout the several figures.

In mining coal it is customary to cut away a portion of the coal at thebottom of the vein and then to bore holes at the top of the vein for thereception of powder or some similar explosive, the coal being throwndown by the explosion of the material in such holes. The object of myinvention is to provide a new and improved drill which is particularlyadapted to be used for boring these holes in which the explosivematerial is placed. I have shown in the drawings a drill A, connectedwith the drill-shaft A, said drill being operated by an electric motorA2. It is of course evident that the drill may be operated by any otherpower, if desired. The electric motor A2 is suspended in a frame A$5 inany desirable manner. The drill-shaft A projects through thearmature-shaft B of the motor, (see Fig. 2,) said armature-shaft beinghollow, so as to receive the drill-shaft. I have not illustrated themechanism of the electric motor, as such mechanism is no part of myinvention and as the construction of such motor is immaterial. Thedrill-shaft A is preferably threaded along a portion of its length, thelength of the threaded portion being at least equal to the longitudinalmovement given the drill. The drill-shaft and the armature-shaft areconnected together so as to rotate as one piece, the connection being`such that the drill-shaft is free to move longitudinally with relationto the armatureshaft. I prefer to connect said drill-shaft andarmature-shaft by providing a keyway C in the drill-shaft, which engagesa key C', seated in the armature-shaft. A feed-nut D surrounds thedrill-shaft and is connected in any convenient manner-as, for example,by means of the pin D-with the friction-disk D2,

said friction-disk being provided with ahan.

die D3. The friction-disk is provided with a hole forv the drill-shaft,said hole being preferably large enou gh to allow the shaft to movefreely with relation thereto. I prefer to construct the feed-nut so thatit may be easily disengaged from the drill-shaft. This may be done bymaking a split nut, as shown, the two parts of which are pivotedtogether at D4, the ends being held in place by the bolt D5 whenthe'feed-nut is operatively connected with the drill-shaft. Thefriction-disk D2 normally bears loosely against the case D6 of themotor, so that the friction-disk is free to revolve with relation tosaid motor. The frame A is provided at its lower end with the projectingpiece A4, which engages the iioor of the mine, and at its upper end withthe adj ustable j ack-screw A5,which is adapted to be brought intocontact with the roof. It will be seen that by this means the frame maybe rigidly held in any desired position. I have described these severalparts in detail, but it is evident that they may be varied in form,construction, and arrangement without departing from the spirit of myinvention, and I therefore do not wish to be limited to the constructionherein shown and described.

I do not, of course, wish to be limited to the form and construction ofthe several parts which constitute the device for feeding the drillforward and the means for releasing the hold of such feed device on thedrill. I have shown a convenient arrangement of devices for thispurpose, but they may be greatly altered and arranged so as to operatein avery different manner. The essential feature is that there should bea device which will under suitable conditions cause the drillshaft to befed forward in its work and which also can be lnanipulated orisassociated with parts which control it so that when the drill is stuckthe hold of the feed device on the drill can be broken, or thefeeddevice can be prevented from holding the drill, so that the drillcan be simply pulled out of engagement with the material upon which itis stuck. Doubtless greatly-modified forms of this device could beeasily gotten up for the purpose of bringing about this result. In theparticular form of this device which I have shown the entire motor ismounted on the frame, but of course this is not essential in all cases.The frame upon which, either with or without the motor, the drill-shaftis supported is put into a fixed position, and the drill-shaft is thenprojected forward with reference to such fixed position of thesupporting-frame, which may or may not include the motor. XVhen thedrill is stuck, it is essential to release the hold which the feedmechanism has on the drill either directly or indirectly, so as torelieve the tension or the back pressure of the drill on the frame, andthis pressure may be exerted direetlyon the frame or, as in the caseillustrated, through the motor. In any event when this pressure betweenthe drill and the supporting-frame is so released by breaking the holdof the feed on the drill the drill can be drawn out more or less, asoccasion may require.

The use and operation of my invention are as follows: Then it is desiredto bore holes in the coal or other material, the drill is placed inposition with its end against the coal or other material and the motorstarted. The backward pressure of the drill due to its engagement withthe coal presses the frictiondisk D2 against the motor-case, and thefriction due to this pressure prevents the disk from rotating. As themotor-shaft revolves it will be seen that the drill will be fed forwardby the threads on the drill-shaft working in the feed-n ut D. It isfound in drilling these holes in coal, for example, that the drill oftencomes in Contact with some hard substance which causes it to bind, thusstopping the motor. This is often done, for example, by balls of sulfuror other hard material. Vhen the drill comes in contact with suchmaterial, it will be stopped, and the only thing that can be (lelie isto back up the drill and give it another start. It will be seen that ifthe drillshaft is rigidly connected with the motorshaft it will be avery difficult matter to do this, for since the drill is stopped in itsforward movement the motor cannot be started, so as to rotate it in theopposite direction. One of the objects of my invention is to allow thedrill to be easily removed under these conditions. If the drill, whenconstructed as herein described, is stopped by any ob stacle, the diskD2 is rotated by means of the handle D3, carrying with it the feed-nutD.

The drillshaft is held stationary Linder these conditions by thearmature. When the drill is working, the pressure of the drill-pointagainst the coal causes the motor-frame to spring backward, and a.pressure is thereby produced tending to move the drill forward. When thedisk and nut are rotated, this pressure is released, and the drill maybe easily disengaged and moved to a position where it can be againstarted. Il' the drill is again stopped, the above operation may berepeated, and if the obstruction is such as to prevent the hole frombeing made the drill maybe easily removed and a new hole started. Thenit is desired to remove the drill from the hole, the split nut isopened, and the drill, being then out of engagement with the threads inthe nut, may be quickly moved backward until it reaches the startingposition. The disk D2 and nut D are also used when there is noobstruction to the drill, for, as before remarked, the backward pressureof the drill causes the frame to spring out of line and press the drillforcibly against the coal. Under these conditions it is difiieulttoremove the split nut until this pressure is released. A movement of thedisk and nut in the man ner described will remove this pressure, and thenut may then be opened and the drill moved to the starting position. Itwill therefore be seen that I have here a construction in which thedrill-shaft has no direct feeding connection with the motor-shaft, thefeeding mechanism being operated by the pressure of the drill againstthe face of the coal.

I claiml. A drill comprising a moving part by which power is conveyed tothe drill-shaft, said drill-shaft being movable longitudinally withrelation to said part and being threaded a portion of its length, afeed-nut engaging said drill-shaft and free to rotate therewith, whenthere is no longitudinal pressure eX- erted on said drill-shaft, saidfeed-nut provided with apart adapted to be forced against an opposedsurface by the pressure produced by the engagement of said drill withthe material upon which it operates, the pressure between the partsholding the nut in position to feed the drill forward.

2. A drill comprising a moving part by which power is conveyed to thedrill-shaft, said drill-shaft free to move longitudinally with relationto said part and threaded a portion of its length, a friction-platemounted upon said drill-,shaft and free to move with relation thereto,said friction-plate having a feednut connected therewith which engagesthe thread on said drill-shaft, said feed-nut being inoperative when thedrill-shaft is free from longitudinal pressure and adapted to be madeoperative by the contact of said fric tion-plate with its opposedsurface.

3. A drill comprising an electric motor provided with a hollowarmatureshaft, a threaded drill-shaft passing through said armatureshaftand feathered thereto so that the drill- TOO IIO

shaft and armature-shaft rotate together, said drill-shaft being free tomove longitudinally with relation to said armature-shaft, afriction-plate mounted upon said drill-shaft and adapted to bear againstthe case of the motor, a normally-inoperative feed -nut connected withsaid friction-plate and in engagement with said drill-shaft, the wholeso arranged that the feed-nut is only made operative so as to feed thedrill-shaft forward when said drill is in engagement with the materialoperated upon.

4:. A drill comprising an electric motor provided with a hollowarmature-shaft, a screwthreaded drill-shaft surrounded by saidarmature-shaft and feathered thereto so as to rotate therewith, saiddrill being free to move longitudinally, a friction-plate mounted uponsaid drill-shaft, and adapted to bear against a stationary opposedsurface, said frictionplate normally free from its opposed surface whenthe drill-shaft is free from longitudinal pressure so as to rotate withsaid drill-shaft, said plate adapted to be brought into contact with itsopposed surface by the engagement of the drill with the material to beoperated on, a normally-inoperative split feed-nut connected with saidfriction-plate, and in engagement with the threads upon saiddrill-shaft, whereby when the drill is stopped by some obstacle thefeed-nut and a friction-plate may be moved relative to saidarmature-shaft so as to release the drill.

5. A drill comprising an electric motor provided with a hollowarmature-shaft, a screwthreaded drill-shaft surrounded by saidarmature-shaft and feathered thereto so as to rotate therewith, saiddrill-shaft being free to move longitudinally, a split feed-nutassociated with said drill-shaft, whereby it is fed forward and areleasing device associated with said mechanism and adapted to releasethe pressure with whichthe drill is forced against the material operatedupon when the motor is stationary so as to allow the feednut to beopened.

6. A drilling-machine comprising a screw' threaded drill-shaft, adriving-motor connected therewith, a normally -inoperative feed-nutassociated with said drill-shaft, a holder for said feed-nut, anengaging surface on the opposite side of the holder from the working endof the drill-shaft against which the holder bears when the shaftcontacts with the material to be operated upon.

7. A drilling-machine comprising an operating-motor, a drill-shaft A', afeed-nut D, a friction-disk D2 connected with said feed-nut, saidfriction-disk and nut free to rotate with the shaft except when thedrill is in contact with the material to be operated upon, substantiallyas described.

CHARLES E. DAVIS. lVitnesses:

DONALD M. CARTER, BERTHA C. SIMS.

